Variable discharge fuel pump



May 15, 1951 M. KATcHER 2,553,321

VARIABLE DISCHARGE FUEL PUMP Filed Nov. 15, 1947 MII-s lll/lll11111111111111111111/if 57 lNvENToR //ae/s ,(WcHsE.

ATTORNEY Patented May 15, 1951 'UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to a variable discharge fuel pump for internal combustion engines. As is well known, a fuel pump, usually a diaphragm operated pump, is inserted in the feed line from the fuel tank to the carburetor. The pump pulls the fuel from the tank and forces it into the carburetor. The pumps of the prior art must be individually designed and constructed to suit the different engines of the various manufacturers. To overcome that part of the variation affecting the operating lever and supportingr bracket of the pump to suit variations in the location of the engine cam shaft for different engines, special types of operating levers and removable supporting brackets have been suggested. Patent No. 2,344,287 to Creveling, my Patent No. 2,440,175, and my pending application Serial No. 660,189`which matured into Patent No. 2,507,339, dated May 9, 1950, treat with this phase of the problem.

However, there is a further variation, a characteristic of the different types of engines, for which provision must be made in order to make the pump more completely universal and that is that different types of engine require, for their best performance, pumps which will deliver fuel at a pressure to suit the pressure predetermined for the carburetor. It is with a pump which has manually adjustable discharge pressures to provide for the latter characteristic that this invention is concerned.

If a pump forces the liquid fuel into the carburetor with too much pressure, there is a waste of fuel consumption. Too little pressure interferes with the proper performance of the engine.

It is an object of the present invention to provide a pump with a spring at the diaphragm whose compressive stress can be adjusted. A

spring is provided which is strong enough for the maximum pressure required to be delivered. The adjustment is able to reduce the pressure of the spring from its maximum. A further adjustment is provided for the spring of the outlet check valve of the pump, the latter serving as the fine adjustment of the discharge pressure, while the former serves as the coarse adjustment.

Other objects and advantages will become apparent upon further study of the description and drawings, in which:

Fig. l is a section of the pump shown with its operating lever engaging a cam on the engine shaft, and with the diaphragm spring adjusted for its maximum compressive action.

Fig. 2 is a partial elevation at the thumb screw and index for adjusting the compression in the spring of the outlet check valve.

Fig. 3 is a partial section taken as in Fig. 1 but showing the diaphragm spring adjusted for its minimum compressive action.

Fig. 4 is a partial sectional plan taken along the line 4 4 of Fig. 3.

Fig. 5 is a fragmental section taken along the line 5-5 of Fig. 4 showing a prong for the diaphragm spring adjustment nested in its hole in the housing and Fig. 6 is a partial elevation taken along the line 6 5 of Fig. 3.

Pump housing 6 has a cover l fastened thereto by screws, one of which is shown at 8. Diaphragm 9 is mounted on the housing 5 by being squeezed between said housing and cover 1. Stem I6) is fastened to diaphragm 9 by means of washers II and I2 which are mounted over the reduced portion I3 of the stem and held by rivet head lli. Stern I 0 is slidably mounted at its lower portion in the horizontal wall I5 of the housing E5. A transverse pin l is provided at the lower end of stem Ill. The hooked inner end of operating lever I'I engages pin I6. Lever II is pivotally mounted by means of pivot I8 on the housing 6. The outer end of lever I'I engages engine cam I9 on the cam shaft 20 of the engine, the latter not being shown. A spring 2| is mounted so as to engage lever I'I at its lower end and housing 6 at its upper end. As cam I9 rotates to bring its high part upwards, it rocks lever I 'I in a clockwise direction against the pressure of spring ZI and then allows said lever to be rocked in the opposite direction by spring ZI when its high part is lowered.

A glass filter bowl 24 is held on top of cover 'I by the usual bail 22 and screw 23. rlhe fuel is received in bowl 24, through an inlet passage, not shown, provided in cover 1.

The fuel received into bowl 2d., when diaphragm 9 is given a downward stroke, passes through nlter screen 25, down into cylindrical member 2t which is formed on cover 'l and eX- tends upward therefrom. From member 26, the fuel passes through inlet check valve 2l into chamber 28. When diaphragm 9 is given an upward stroke the fuel is pushed out of chamber 28 into passage 29 formed in cover 1.'

An outlet ball check valve 3l! is provided in passage 29. The valve 3l! is held on its seat by one end of spring 38 pressing against spring plug 38. The other end of spring 38 reacts against piston All slidably mounted in passage 29. The outer end of passage 2S is closed by screw plug 4I. Threaded into a hole provided in screw plug 4I is an adjusting screw 43 having a knurled head 42. As screw d3 is screwed inward in plug lll, its inner end pushes against piston il?, increasing the compressive stress in spring 3%. When screw 43 is screwedoutward, it reduces the compression in spring 38. I-n order to be able to visualize the adjustment of the compression in spring 38 and to control its neness, an index finger IM is fastened to head 42,

which nger rides over a scale 45 provided on ange 49 located at the outer end of passage 29.

The compression or upper stroke of diaphragm 9 forces the uid from chamber 28 into passage 29 and past ball check valve 3, from whence it is discharged from outlet 41.

Encircling stem I3 and extending from washer l2 at the top to adjusting member 3i at the bottom is diaphragm spring 32. Member 3l also encircles stern I6. It is guided in rotation about said stem by three upstanding lugs i3 whose inner surfaces fall on a circle Whose center is on the vertical axis of stem l0. The bottom of member 3| is provided with three tongues 33 which are inclined at one edge. Wall i5 is provided with three corresponding slots 34 for receiving tongues 33 when member 3| is turned into position for their registration. As seen in Fig. 3, member 3i is in its lowest position when said registration occurs. When member 3l is turned counterclockwise, as seen in Fig. 4, from its position of registration, the inclined edge of tongues engage a corresponding inclined edge of slots 343 causing member Si to rise into the position shown in Fig. 1. The bottom of tongues 33 then rest on top of wall Hi. The compression in spring 32 is at its maximum when tongues 33 rest on top of wall l5 and said compression is at its minimum when the tongues are fully down in slots 34. Member 3i is provided with an arm 35 for manually rotating it, so that tongues 33 are brought in and out of slots 34. Arm 35 is provided with an upturned finger i9 at its outer end coming just outside of housing 3. A slot 59 is provided in finger 49 in which slides set screw 5 l. The latter is screwed into a suitable hole provided in housing 6 and is used to lock finger le and with it member 3i in the position in which it is manually set for controlling the compression in spring 32.

A lug 32 is provided under arm 35 to serve as a iinger grip to be used in turning said arm.

The downward or suction stroke of diaphragm S is positively effected by the engagement of the hooked end of lever Il with pin I3, but the upward or compression stroke depends on the compression in spring 32. rlIhe stronger the compressive stress of spring 32, the stronger is the pressure induced in chamber 28 by diaphragm 9. By adjusting the compression in spring 32 by lowering or raising member 3i, the pressure in chamber 28 is ylowered or 'raised as desired. As noted above, this adjustment serves to t the discharge pressure of the pump for the particular engine with which it is to be used. However, because of the coarseness of this adjustment, a further 'and finer adjustment vis helpful for a more exact fitting of the discharge pressure of the pump to that required for the particular engine Y with which it is to be used. By turning adjusting screw 43 so that it is screwed inward, piston 40 Vis moved inward, increasing the compression in spring 38 and thereby holding ball valve more tightly against its seat. This will decrease 'the pressure of fluid discharged from outlet si. Turning adjusting screw 43 so that it is screwed outward, will reduce the compression in spring 33, permitting fluid to be discharged from outiet 41 at greater pressure.

By increasing the compression in spring uid is discharged from cham-ber 23 at increased pressure which pressure combined with the pressure induced by spring 33 controls the nal pressure of the lfluid discharged from outlet li'i. 1f the compression in spring 33 is increased, it will detract more from the pressure induced in the fluid by spring 32, than if the compression in spring 38 is reduced.

I claim:

1. For use in a fuel pump having a housing providing a fuel pump chamber and having movably mounted means, adapted to be given a compression stroke and a suction stroke in the housing, cooperating with said chamber for pumping fuel, said means being engaged by one end of a compression spring for eifecting its compression stroke, a transverse part in the housing fixed thereto and located opposite the other end of the spring for taking its reaction, a member rotatably mounted on said part between said other end of the spring and said part, said member being movable axially with respect to said part and the spring, the spring acting to press the member against said part, said part being prcvided with a plurality of circumferentially spaced. slots, and a plurality of projections extending from said member toward said part, the projections being formed and located on the member to mate with the slots when turned into register therewith, an edge of each projection being beveled, whereby when the beveled edge of the projections is forced against an end of the slots, the member is caused to separate from said part, thereby increasing the compressive stress in the spring.

2. For use in a fuel pump having a movable member, as claimed in claim 1, a ringer on the movable member extending outside of the housing, and a fastening device formed to releasably fasten the portion of the finger outside of the housing to the housing .for locking the member to the housing in various circumferential positions.

3. For use in a fuel pump having a movable member, as claimed in claim 1, a finger on the movable member extending to the outside of the housing with a portion outside of the housing extending axially thereof, and a fastening device formed to releasably fasten to the housing the axially extending portion of the finger for locking the member to the housing in various circumferential positions.

4. For use in a fuel pump having a finger, as claimed in claim 3, in which said finger is provided with a circumferentially and axially extending slot, and a screw for slidably engaging and passing through the slot into threaded engagement with the housing, said screw, when screwed sufficiently into the housing, gripping the finger in the position the finger is set.

MORRIS KATCHER.

REFERENCES CITED The following references are of record in the file 0f this patent:

UNITED STATES PATENTS Number Name Date 1,050,048 Zimmer dan. 7, 1913 1,885,436 Hampton Nov. 1, 1932 1,902,930 Zubaty Mar. 28, 1933 1,919,040 Rockwell July 18, 1933 2,108,079 Schey et al. Feb. 15, 1933 2,276,568 Erickson Mar. 17, 1942 2,286,928 Pipkin June 16, 1942 2,291,912 Meyers Aug. 4, 1942 2,344,287 Creveling Mar. 14, 1944 2,440,175 Katcher Apr. '20, 1948 2,507,339 Katcher May 9, 1950 

